Concentric Architecture for Optical Sensing

ABSTRACT

An electronic device including optical sensing with a concentric architecture and methods for operation thereof is disclosed. The concentric architecture can include light detector(s) arranged in a concentric manner around light emitter(s). In some examples, at least one light emitter can be located in the center of the device, and each light detector can be located the same separation distance from the light emitter. Each light detector can be arranged such that the separation distance from the centrally located light emitter can be greater than the separation distance from another light emitter. Examples of the disclosure further include a selective transparent layer overlaying the light detector(s). The selective transparent layer can include section(s) transparent to a first wavelength range and non-transparent to a second wavelength ranges. In some examples, the selective transparent layer can further include section(s) transparent to the second wavelength range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/126,970, filed Sep. 10, 2018, which claims the benefit of U.S.Provisional Patent Application No. 62/563,594, filed Sep. 26, 2017, theentire disclosures of which are incorporated herein by reference intheir entirety.

FIELD

This relates generally to architectures for optical sensing. Moreparticularly, the disclosure relates to architectures for an opticalsensing unit including a plurality of light detectors arranged in aconcentric manner around a plurality of light emitters.

BACKGROUND

A photoplethysmogram (PPG) signal can be measured by optical sensingsystems to derive corresponding physiological signals (e.g., pulserate). In a basic form, the optical sensing systems can employ a lightemitter that emits light through an aperture and/or window into theuser's tissue. In addition, a light detector can be included to receivelight through an aperture and/or window. The light received by the lightdetector can be light that has returned (e.g., reflected or scattered)and exited the tissue. In some instances, optical losses due to one ormore components in the system may affect the determination of the user'sphysiological information.

SUMMARY

This disclosure relates to an electronic device configured for opticalsensing having a concentric architecture and methods for operationthereof. The concentric architecture can include a plurality of lightdetectors arranged in a concentric manner around a plurality of lightemitters. The plurality of light emitters can include a plurality offirst light emitters emitting at a first wavelength range (e.g., visiblewavelengths) and one or more second light emitters emitting at a secondwavelength range (e.g., infrared wavelengths). In some examples, atleast one second light emitter can be located in the center of thedevice, and each light detector can be located the same separationdistance from the at least one second light emitter. Each light detectorcan be arranged such that the separation distance from the centrallylocated second light emitter can be greater than the separation distancefrom a first light emitter.

Examples of the disclosure further include a selective transparent layeroverlaying the plurality of light detectors. The selective transparentlayer can include a plurality of first sections transparent to a secondwavelength range (e.g., infrared wavelengths) and non-transparent to afirst wavelength ranges (e.g., visible wavelengths). The selectivetransparent layer can further include a plurality of second sectionstransparent to the second wavelength range. In some examples, a Fresnellens can be located in a corresponding region of the first and secondlight emitters. The Fresnel lens can include a plurality of regions,such as a first region and a second region. The first region can belocated in the field of view(s) of the first light emitter(s), and thesecond region can be located in the field of view(s) of the second lightemitter(s). The plurality of regions of the Fresnel lens may havedifferent optical (e.g., percent transmission, amount of collimation,etc.) properties.

Methods for operating the optical sensing unit can include associatingthe plurality of light detectors to one or more channels. Each lightemitter is sequentially activated to emit light, and the one or morechannels can further sequentially measure light from the given lightemitter. In some examples, the association of the one or more channelscan be dynamically changed. For example, during a first time, all of theplurality of light detectors can be associated to a single channel. Thesystem can dynamically change, during a second time, to the plurality oflight detectors being associated to multiple channels. In some examples,the device can be configured to perform multiple measurement types(e.g., primary and secondary measurements) as part of a samplingprocedure, where the primary measurements can include readings using afirst set of operating conditions of the PPG sensor unit, and thesecondary measurements can use a different second set of operatingconditions of the PPG sensor unit. The single channel can be used forthe primary measurements, and the multiple channels can be used for thesecondary measurements, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate systems in which examples of the disclosure canbe implemented.

FIG. 2A illustrates a top view of an exemplary electronic deviceincluding a concentric architecture for optical sensing according toexamples of the disclosure.

FIG. 2B illustrates the cross-sectional view of FIG. 2A along line I-IIaccording to examples of the disclosure.

FIG. 2C illustrates a top view of an exemplary concentric architectureincluding a selective transparent layer overlaid according to examplesof the disclosure.

FIG. 2D illustrates an enlarged view of an exemplary selectivetransparent layer overlaying a single light detector according toexamples of the disclosure.

FIG. 2E illustrates a cross-sectional view of an exemplary electronicdev ice including a concentric architecture and a retroreflectoraccording to examples of the disclosure.

FIG. 2F illustrates a cross-sectional view of an exemplary electronicdev ice including a concentric architecture, a retroreflector, and anopaque mask according to examples of the disclosure.

FIG. 2G-2H illustrate cross-sectional and top views, respectively, of anexemplary electronic device including a lens with multiple regionsaccording to examples of the disclosure.

FIG. 3 illustrates an exemplary process flow using a binning techniquefor one or more channels according to examples of the disclosure.

FIGS. 4A-4E illustrate exemplary associations of the light detectors tochannels according to examples of the disclosure.

FIG. 5 illustrates an exemplary block diagram of a computing systemcomprising light emitters and light detectors for measuring a signalassociated with a user's physiological state according to examples ofthe disclosure.

FIG. 6 illustrates an exemplary configuration in which an electronicdevice is connected to a host according to examples of the disclosure.

DETAILED DESCRIPTION

In the following description of examples, reference is made to theaccompanying drawings in which it is shown by way of illustrationspecific examples that can be practiced. It is to be understood thatother examples can be used and structural changes can be made withoutdeparting from the scope of the various examples. Numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects and/or features described or referenced herein. Itwill be apparent, however, to one skilled in the art, that one or moreaspects and/or features described or referenced herein may be practicedwithout some or all of these specific details. In other instances,well-known process steps and/or structures have not been described indetail in order to not obscure some of the aspects and/or featuresdescribed or referenced herein.

A photoplethysmographic (PPG) signal can be measured by an opticalsensing system to derive corresponding physiological signals (e.g.,pulse rate). Such optical sensing systems can be designed to besensitive to changes in a user's tissue that can result fromfluctuations in the amount or volume of blood or blood oxygen in thevasculature of the user. In a basic form, optical sensing systems canemploy a light emitter or light emitter that emits light through anaperture and/or window into the user's tissue. The system can furtherinclude a light detector to receive return light (i.e., light that hasreflected and/or scattered and exited the tissue) through the same oranother aperture and/or window. The PPG signal is the amplitude ofreturn light that is modulated with volumetric change in blood volume inthe tissue. The light emitters and light emitters in the optical sensingsystem can be arranged in a concentric architecture.

This disclosure relates to an electronic device configured for opticalsensing having a concentric architecture and methods for operationthereof. The concentric architecture can include a plurality of lightdetectors arranged in a concentric manner around a plurality of lightemitters. The plurality of light emitters can include a plurality offirst light emitters emitting at a first wavelength range (e.g., visiblewavelengths) and one or more second light emitters emitting at a secondwavelength range (e.g., infrared wavelengths). In some examples, atleast one second light emitter can be located in the center of thedevice, and each light detector can be located the same separationdistance from the at least one second light emitter. Each light detectorcan be arranged such that the separation distance from the centrallylocated second light emitter can be greater than the separation distancefrom a first light emitter.

Examples of the disclosure further include a selective transparent layeroverlaying the plurality of light detectors. The selective transparentlayer can include a plurality of first sections transparent to a secondwavelength range (e.g., infrared wavelengths) and at least partiallynon-transparent to a first wavelength ranges (e.g., visiblewavelengths). The selective transparent layer can further include aplurality of second sections transparent to the second wavelength range.In some examples, a Fresnel lens can be located in a correspondingregion of the first and second light emitters. The Fresnel lens caninclude a plurality of regions, such as a first region and a secondregion. The first region can be located in the field of view(s) of thefirst light emitter(s), and the second region can be located in thefield of view(s) of the second light emitter(s). The plurality ofregions of the Fresnel lens may have different optical (e.g., percenttransmission, amount of collimation, etc.) properties.

Methods for operating the optical sensing unit can include associatingthe plurality of light detectors to one or more channels. Each lightemitter is sequentially activated to emit light, and the one or morechannels can further sequentially measure light from the given lightemitter. In some examples, the association of the one or more channelscan be dynamically changed. For example, during a first time, all of theplurality of light detectors can be associated to a single channel. Thesystem can dynamically change, during a second time, to the plurality oflight detectors being associated to multiple channels. In some examples,the device can be configured to perform multiple measurement types(e.g., primary and secondary measurements) as part of a samplingprocedure, where the primary measurements can include readings using afirst set of operating conditions of the PPG sensor unit, and thesecondary measurements can use a different second set of operatingconditions of the PPG sensor unit. The single channel can be used forthe primary measurements, and the multiple channels can be used for thesecondary measurements, for example.

Representative applications of the apparatus and methods according tothe present disclosure are described in this section. These examples arebeing provided solely to add context and aid in the understanding of thedescribed examples. It will thus be apparent to one skilled in the artthat the described examples may be practiced without some or all of thespecific details. Other applications are possible, such that thefollowing examples should not be taken as limiting.

FIGS. 1A-1C illustrate systems in which examples of the disclosure canbe implemented. FIG. 1A illustrates an exemplary mobile telephone 136that can include a touch screen 124. FIG. 1B illustrates an exemplarymedia player 140 that can include a touch screen 126. FIG. 1Cillustrates an exemplary wearable device 144 that can include a touchscreen 128 and can be attached to a user using a strap 146. The systemsof FIGS. 1A-1C can utilize the optical layers, the optical films, thelenses, the window systems, the concentric architecture, and/or methodsfor detecting a PPG signal as will be disclosed.

Exemplary Configuration of the Optical Sensing Unit

FIG. 2A illustrates a top view of an exemplary electronic deviceincluding a concentric architecture for optical sensing according toexamples of the disclosure. The top view in FIG. 2A can be viewed as theunderside of wearable device 144 of FIG. 1C, for example. Further, thetop view in FIG. 2A includes a partial top view of device without aselective transparent layer (discussed below) overlaid.

Device 200 can include a plurality of light detectors 204A, 204B, 204C,204D, 204E, 204F, 204G, and 204H (collectively referred to as pluralityof light detectors 204); a plurality of first light emitters 206A, 206B,206C, and 206D (collectively referred to as plurality of first lightemitters 206); and a plurality of second light emitters 208A and 208B(collectively referred to as plurality of second light emitters 208).The device 200 can be situated such that the plurality of lightdetectors 204, the plurality of first light emitters 206, and secondlight emitter 208 are proximate to the user's skin. For example, thedevice 200 can be held in a user's hand or strapped to a user's wrist,among other possibilities.

The device can include a plurality of regions such as the center region209 and the peripheral region 205. The center region 209 can beseparated from the peripheral region 205 by an optical isolation (e.g.,optical isolation 216), where the peripheral region 205 can be locatedcloser to the edges (e.g., edge 201C) of the device 200 than the centerregion 209. For example, the center region 209 can include a pluralityof light emitters (e.g., first light emitters 206 and second lightemitters 208). In some examples, the plurality of first light emitters206 can be located closer to the peripheral region than at least onesecond light emitter 208 (e.g., second light emitter 208A). In someexamples, at least one second light emitter 208 (e.g., second lightemitter 208A) can be located in the center of the center region 209. Insome examples, the plurality of first light emitters 206 can beconfigured to emit a different range(s) of wavelengths (e.g., greenwavelengths) than the second light emitter(s) 208 (e.g., second lightemitters can be configured to emit infrared wavelengths). The peripheralregion 205 can partially or entirely surround the center region 209.

In some examples, the separation distances and locations of the lightdetectors and light emitters can optimized for different types ofmeasurements (e.g., primary and secondary measurements). For example,the second light emitter 208A can be located in the center of device 200and can be configured to emit infrared light for detecting one type ofinformation. The center of device 200 can be such that the distancesfrom second light emitter 208A to the edges of device 200 along the samedirection (e.g., left-to-right and/or top-to-bottom) are the same. Forexample, the distance from the top edge 201A of the device and secondlight emitter 208A can be the same as the distance from the bottom edge201B of the device. The distance from the left edge 201C of the deviceand second light emitter 208A can be the same as the distance from theright edge 201D of the device. Optionally, device 200 can include secondlight emitter 208B also used for detecting the same type of informationas the second light emitter 208A.

The plurality of first light emitters 206 can be placed closer to theperipheral region 205. For example, the plurality of first lightemitters 206 can include four light emitters: first light emitter 206A,first light emitter 206B, first light emitter 206C, and first lightemitter 206D, which can be arranged to form a square, rectangle,quadrilateral, or the like. For example, the plurality of first lightemitters 206 can be arranged in a square where the separation distancesbetween first light emitter 206A and first light emitter 206B, betweenfirst light emitter 206B and first light emitter 206C, between firstlight emitter 206C and first light emitter 206D, and between first lightemitter 206D and first light emitter 206A can be the same. In someexamples, the separation distances between each first light emitter 206and the center second light emitter 208A can be the same. Although thefigure illustrates the plurality of first light emitters 206 as locatedthe same separation distance from optical isolation 216, examples of thedisclosure can include the light emitters being separated at varyingdistances. Further, examples of the disclosure are not limited to thelight emitters located in a square-like arrangement, and pairs of firstand second light emitters are not limited to having the same separationdistances.

The peripheral region 205 can be located around (partially or entirely)the center region 209. The plurality of light detectors 204 can beradially arranged in the peripheral region 205. In some examples, aradial arrangement can include the plurality of light detectors 204 asoriented with an angle of a given edge dependent on the location in theperipheral region 205, where each light detector 204 has the same orsimilar shape. For example, an angle of a top edge 214 (e.g., edge ofthe light detector closest to the edges of the device) of light detector204A and light detector 204E can be at 0°. Top edge 214 of lightdetector 204B and/or light detector 204F can be 45° relative to the topedge 214 of light detector 204A and/or light detector 204E. Top edge 214of light detector 204D and/or light detector 204H can be −45° relativeto the top edge 214 of light detector 204A and/or light detector 204E.Top edge 214 of light detector 204C and/or light detector 204G can be90° or −90° relative to top edge 214 of light detector 204A and/or lightdetector 204E. In this manner, the top edges 214 of two or more lightdetectors 204 can have different angles of orientation.

The relative arrangement of the light emitters and light detectors canbe such that the distance (i.e., separation distance D₂) between a firstlight emitter 206 (e.g., first light emitter 206A) and its closest lightdetector 204 (e.g., light detector 204A) can be less than the distance(i.e., separation distance D₁) between a second light emitter 208 (e.g.,second light emitter 208A) and the same light detector 204. Ininstances, the first light emitter 206A can be a LED that emits visiblelight (e.g., green light) that has a separation distance D₂ to one lightdetector 204A that is shorter than the separation distances to the otherlight detectors, such as the light detectors 204B-204H. The term“separation distance” means the distance measured from the center of onecomponent to the center of the other component. In some examples, theseparation distance between a first light emitter 206 and its closestneighboring light detectors 204 can be the same. Additionally, thedistance (e.g., separation distance D₃) between the same closest firstlight emitter 206 (e.g., first light emitter 206A) and another lightdetector (e.g., light detector 204E) can be greater than both theseparation distance D₁ and the separation distance D₂, as illustrated inthe figure.

In some examples, the second light emitter 208A can be an infrared lightemitter configured for one type of measurement, and the first lightemitter 206A can be a visible (e.g., green wavelengths) light emitterconfigured for another type of measurement. In some examples, the lightdetectors associated with the separation distance D₁ and the separationdistance D₃ can have the same angle of orientation. For example, thelight detector 204A and the light detector 204E can both have a top edge214 orientated at 0°.

In some examples, each light detector can be configured such that anedge “aligns” with a light emitter. For example, the center of the firstlight emitter 206A can be along the same y-plane as the center of thelight detector 204A. In this manner, the separation distance D₂ betweencenters of a first light emitter (e.g., the first light emitter 206A)and its closest light detector (e.g., light detector 204A) is less thanthe separation distances between the center of the same first lightemitter and others of the plurality of light detectors 204.

In other examples, the first light emitter 206A can be located betweenthe edges of adjacent light detectors 204A and 204H, as shown in FIG.2C. That is, the radial angle of first light emitter 206A can be thesame as the radial angle of the edges of light detector 204A and lightdetector 204H. In this manner, the separation distances between thecenter of a light emitter (e.g., first light emitter 206A) and thecenter of its two closest light detectors (e.g., light detector 204A and204H and/or two adjacent light detectors) can be the same. Although thefigure illustrates eight light detectors 204 and four first lightemitters 206, examples of the disclosure can include any number of lightdetectors and any number of light emitters. Further, although the figureillustrates the light detectors 204 as having rectangular-shapeddetection areas and the light emitters as having square-shared emittingareas, examples of the disclosure can include any shape.

The device 200 can include one or more components for enhanced opticalcollection, signal generation, and/or reduced noise. FIG. 2B illustratesthe cross-sectional view of FIG. 2A along line I-II. The one or morecomponents can include optical isolation 216, optical film 240, andFresnel lens 242. To prevent or reduce optical crosstalk between theplurality of light detectors 204 and the plurality of first lightemitters 206, optical isolation 216 can be a wall located between theplurality of light detectors 204 and the plurality of first lightemitters 206. The optical isolation 216 can thereby define the cavity ofthe light emitters, separate from the cavity or cavities of the lightdetectors. The optical isolation 216 can be located in the center region209 and/or in the peripheral region 205. In some examples, the opticalisolation 216 located in center region 209 can include the same material(or be formed from a continuous piece of material) as included in theoptical isolation 216 located in peripheral region 205. In someinstances, the optical isolation 216 can be a concentric ring. In someexamples, the optical isolation 216 may be different from other types ofisolation that may be included in the device. Optical isolation 216 maycollectively form at least two cavities which the light emitters andlight sensors may be located within. Other types of isolation mayinclude, but are not limited to, optical, electrical, and/or mechanicalisolation of the optical sensing system from other components (e.g., adisplay or a touch screen) included in the device.

The optical film 240 can be a film configured for light restriction(discussed in detail below). The optical film 240 can at least partiallyoverlay the section of window 203 corresponding to light passing throughto at least one light detector 204. In some examples, device 200 caninclude one section of optical film 240 disposed over each lightdetector 204. The optical film 240 can have other arrangements such asbeing attached to a window, being disposed on a window, being disposedon a detector, and the like. In some examples, a single (e.g.,ring-shaped) optical film 240 can be disposed over a plurality(including all) of light detectors 204. In some examples, the edges ofoptical film 240 can extend to (e.g., contact) the optical isolation216.

The Fresnel lens 242 can be a lens configured to direct and/or focuslight emitted by the light emitters. The Fresnel lens 242 can at leastpartially overlay the section of window 203 corresponding to lightpassing through from the plurality of first light emitters 206 and/orthe second light emitter(s) 208. That is, the Fresnel lens 242 can belocated in the field of view of the plurality of first light emitters206 and the field of view of the plurality of second light emitters 208.The Fresnel lens 242 can be configured for one or more targeted types ofmeasurements. In some examples, the Fresnel lens 242 can be configuredfor obscuration of the light emitters. For example, the features of theFresnel lens 242 can be based on achieving optimal measurementsassociated with the second light emitter 208 and associated with theplurality of first light emitters 206, while also reducing thevisibility of the light emitters.

Additionally, device 200 can include one or more layers for reducingvisibility of other components. Opaque mask 219 can be configured toreduce visibility optical isolation 216 and/or the edge of optical film240 by being opaque at one or more wavelengths (e.g., the wavelengthsbeing measured by the device). In some examples, a portion of opaquemask 219 can extend past the walls of the cavities (e.g., created byoptical isolation 216). In some examples, the opaque mask 219 and theoptical isolation 216 can include the same materials and/or functions(e.g., act as an optical isolation and/or cosmetic layer). At least oneend of the opaque mask 219 and/or the optical isolation 216 can belocated at or in close proximity to the internal surface (i.e., surfacefurthest from the exterior surface of the housing of device 200) ofwindow 203. The device 200 further can include an adhesive 215configured to adhere one or more components (e.g., optical film 240,opaque mask 219, etc.) to the window 203.

FIG. 2C illustrates a top view of the concentric architecture includingthe selective transparent layer overlaid according to examples of thedisclosure. FIG. 2D illustrates an enlarged view of the selectivetransparent layer overlaying a single light detector according toexamples of the disclosure. A selective transparent layer 210 can belocated in a peripheral region (e.g., peripheral region 205 illustratedin FIG. 2A). The selective transparent layer 210 can be configured toconceal routing traces and the contact pads 212 and/or edges of theplurality of light detectors 204. In this manner, the selectivetransparent layer 210 can be located between the optical film 240 andthe adhesive 215. The selective transparent layer 210 can include one ormore first sections 211A of material that is at least partiallytransparent to a second wavelength range (e.g., infrared wavelengths) oflight, wherein the transparency can be configured to allow light toreach the plurality of light detectors 204 for, e.g., a secondarymeasurement. The selective transparent layer 210 can also include one ormore second sections 211B overlaying a central portion of each lightdetector 204 to allow light of a first wavelength range (e.g., visiblewavelengths) to reach the plurality of light detectors 204 for, e.g., aprimary measurements. The one or more second sections 211B overlayingthe central portion can include material transparent to the secondwavelength range or may be omitted material (e.g., an opening). In someinstances, the one or more second sections 211B can also be transparentto the first wavelength range.

In some examples, the first section(s) 211A can be partially transparent(i.e., partially blocks) a first wavelength range and fully transparentto a second wavelength range.

The selective transparent layer 210 can be located anywhere in the fieldof view of the plurality of light detectors 204. For example, theselective transparent layer 210 can be located between the optical film240 and the window 203. Examples of the disclosure can include theselective transparent layer 210 as being a layer separate from thewindows 203. In other instances, the selective transparent layer 210 canbe formed in the window 203.

In some examples, the device can include one or more componentsconfigured to redirect light that may not include physiologicalinformation, thereby preventing the unwanted light from reaching thelight detector. FIG. 2E illustrates a cross-sectional view of anexemplary electronic device including a concentric architecture and aretroreflector according to examples of the disclosure. The device 200can include a retroreflector 233 located proximate to the opticalisolation 216. In some instances, the retroreflector 233 may beimplemented as a component of the optical sensing unit. Theretroreflector 233 can replace the opaque mask 219 illustrated in FIG.2C and can be located between the center region 209 (including the firstlight emitters 206 and the second light emitters 208) and the peripheralregion 205 (including the light detectors 204). The retroreflector 233may be a ring or an arc that is located around the center region 209.Alternatively, the retroreflector 233 can be located in one or moresections of the ring, while an opaque mask (e.g., opaque mask 219) canbe located in one or more other sections of the ring. In some examples,one or more sections of the ring may not include a retroreflector 233 oran opaque mask 219.

The retroreflector 233 can be a component capable of reflecting lightback along a direction that is parallel or nearly parallel to, butopposite in direction from its origin, irrespective of the angle ofincidence. For example, light from the light emitters 206 may reflectoff an interface (e.g., the outer surface, which may be the surfaceopposite the retroreflector 233) of the window 203. The light may reachthe light detector 204 without interacting with the sample, and thus maynot include physiological information. Instead of allowing the light toreach the light detector 204, the retroreflector 233 may reflect thelight back to the interface (e.g., in the direction away from the lightdetector 204).

In some examples, the retroreflector can include one or more featureshaving properties (e.g., 20 degrees, 60 degrees, 90 degrees, etc.)configured to selectively reflect light within a range of angles ofincidence. In some examples, the one or more features can reflect lightback in the same direction that is not parallel or nearly parallel tothe incident light. In some examples, the retroreflector 233 may bewavelength independent, where a wide range of wavelengths can bereflected back.

In some instances, the device 200 can include both a retroreflector 233and an opaque mask 219, as illustrated in FIG. 2F. The retroreflector233 can be located closer to the light emitters 206 and 208 (and/orlight detector 204C) than the opaque mask 219. The opaque mask 219 canfurther help to prevent unwanted light from reaching the light detector204 by including a material that can absorb the light rays that reflectoff the one or more interfaces of the window 203. In some examples, asillustrated in the FIGS. 2E-2F, the retroreflector 233 and/or the opaquemask 219 can have a larger width (e.g., can overhang) than the opticalisolation 216, which can reduce the cross-talk between the lightemitters 206 and 208 and the light detectors 204. In some examples, theopaque mask 219 can have a smaller width than the retroreflector 233.Additionally or alternatively, the retroreflector 233 and/or the opaquemask 219 can include one or more materials (e.g., black ink) thatconceal underlying components (e.g., optical isolation 216) from theuser's eyes.

In some examples, the device 200 can include a lens having multipleregions. FIG. 2G-2H illustrate cross-sectional and top views,respectively, of an exemplary electronic device including a lens withmultiple regions according to examples of the disclosure. The device 200can include lens region 242A and lens regions 242B (collectivelyreferred to as lens 242). The different lens regions can have differentoptical and/or physical properties. For example, the lens region 242Acan be a Fresnel lens that overlays (i.e., located in the field of viewof) the second light emitter 208A. The lens regions 242A can include aplurality of features (e.g., ridges) for focusing (e.g., collimating thelight emitted by the second light emitter 208A. The lens regions 242Bcan overlay at least two of the plurality of first light emitters 206.The lens regions 242B can include one or more other features (e.g.,prisms) for controlling the light emitted by the plurality of firstlight emitters 206.

In some instances, the lens 242 can be a layer separate from the windows203. In other examples, the lens 242 can be formed as a part of (i.e.,inseparable from) the windows 203.

In instances where the second light emitter(s) 208 emit a second lighthaving a second wavelength, such as infrared light, and the first lightemitters 206 emit a first light having a first wavelength, such asvisible (e.g., green) light, the properties of the second light maydiffer from the first light. For example, the second light may have alower signal intensities (or signal-to-noise ratio (SNR)), and the lensregion 242A (associated with the second light) may have one or moreproperties for enhancing the relative signals or SNR.

Exemplary Operation of the Sensing Unit

The sensing unit can be operated using one or more binning techniques.FIG. 3 illustrates an exemplary process flow using a binning techniquefor one or more channels according to examples of the disclosure. One ormore light detectors (e.g., all of the plurality of light detectors 204)can be associated with one or more channels (step 352 of process 350).In some examples, the channels can be dynamically changed based on theselected light emitter (step 353 of process 350). In some examples, thechannels can be dynamically changed based on the spacing.

For a given channel, one or more light emitters (e.g., second lightemitter 208A) can emit light (e.g., infrared light) (step 354 of process350). A portion of the light can be absorbed by the user's skin,vasculature, and/or blood, and a portion of the light can return to thelight detectors. The light detector(s) associated with the given channelcan measure the return light and can generate one or more signalsindicative of the measured return light (step 356 of process 350). Thesignals in the channel may be read out and processed (e g, summed)together, for example, to produce a channel signal (step 358 of process350). The process can measure channels sequentially or concurrently. Inthe scenarios where the channels are measured sequentially, the processcan be repeated for other channels until some or all channels aremeasured for a given light emitter. In some examples, multiple(including all) channels may be readout simultaneously, where signalswithin the same channel are processed separately from signals from otherchannels. Another light emitter (e.g., first light emitter 206A) can beselected for the measurements (step 364 and step 366 of process 350).Measuring multiple light emitters can allow the system to measuremultiple regions of the user's skin for enhanced measurement accuracy.From the binned signals, the physiological information can be determined(step 368 of process 350).

Examples of the disclosure can include a single channel wherein some(including all) of the light detectors are associated with the singlechannel. With a single channel, all the signals from all of theplurality of light detectors can be processed together. The singlechannel association can allow higher total signal collection, which canincrease the SNR for the light emitter 408A. Examples of the disclosurecan further include each light detector associated with a uniquechannel. For example, the system can be configured with eight lightdetectors and eight channels. In this manner, the signal from each lightdetector can be processed separately.

Additionally or alternatively, the system can be configured with otherassociations. FIGS. 4A-4E illustrate exemplary associations of the lightdetectors to channels according to examples of the disclosure. FIG. 4Aillustrates two channels, where light detectors (e.g., light detector404A, light detector 404B, light detector 404C, and light detector 404D)located on one side of the device can be associated with a first channel420, and light detectors (e.g., light detector 404E, light detector404F, light detector 404G, and light detector 404H) located on the otherside of the device can be associated with a second channel 421. Theunique relationships between each light emitter relative to the channelscan lead to different information. Generally, the signal information mayinclude a higher signal intensity for shorter separation distancesbetween a light emitter and a light detector. When one light emitter isemitting light (i.e., activated), the signal information measured byeach channel may be the same. For example, when light emitter 406A isemitting light, the light can be detected by all of the light detectorsassociated with a given channel. Channel 420 and channel 421 can includehigh signal information from light detector 404A and light detector404H, respectively, along with low signal information from lightdetector 404D and light detector 404E, respectively. When another lightemitter is emitting light, the signal information measured by eachchannel may differ. For example, when light emitter 406B is emittinglight, channel 420 may include high signal information from lightdetector 404B and light detector 404C, along with moderate signalinformation from light detector 404A and light detector 404D. Channel421 may include low signal information from light detector 404E, lightdetector 404H, light detector 404F, and light detector 404G. In thismanner, the same light detectors can measure different sets of signalsdepending on which light emitter is activated.

Although the figure illustrates one channel as including the lightdetectors located on the right side and the other channel as includingthe light detectors located on the left side, examples of the disclosurecan include the same number (e.g., two) of channels, but theassociations including different light detectors. For example, thechannel 420 can include the light detector 404C, the light detector404D, the light detector 404E, and the light detector 404F, while thechannel 421 can include the light detector 404G, the light detector404H, the light detector 404A, and the light detector 404B (not shown).In some examples, the channel associations can be based on the relativelocation of the light emitter.

FIG. 4B illustrates four channels according to examples of thedisclosure. Each channel can include two adjacent light detectors withan emitter having the same separation distance relative to the centersof the light detectors. For example, the channel 422 can include thelight detector 404A and the light detector 404H; the channel 423 caninclude the light detector 404B and the light detector 404C; the channel424 can include the light detector 404D and the light detector 404E; andthe channel 425 can include the light detector 404F and the lightdetector 404G. The unique relationships between each light emitterrelative to the channels can lead to different information. For example,the signal from the channel 422 can include different information thenthe channel 424 when the light emitter 406A is activated. With a highernumber of channels (e.g., relative to the two channel associationillustrated in FIG. 4A), localization of the measurement region on theuser's skin can be enhanced, thereby increasing the SNR for themeasurements. The localization of a measurement region can refer to theamount of information in the signal that is from the region proximate toa given light detector(s).

FIG. 4C illustrates two channels, wherein the channels may benon-uniformly allocated. In some instances, the number of lightdetectors associated with each channel can differ. For example, thechannel 426 can include six light detectors (e.g., the light detector404C, the light detector 404D, the light detector 404E, the lightdetector 404F, the light detector 404G, and the light detector 404H),and the channel 427 can include two light detectors (e.g., the lightdetector 404A and the light detector 404B). The system can be configuredsuch that signals from one channel may be utilized for one type ofinformation, and the signals from the other channel may be utilized foranother type of information. For example, the channel 427 may haveincreased localization of a targeted measurement region on the user'sskin and can be used for determining the user's physiologicalinformation. With decreased localization, channel 426 can be used foroff-wrist detection and/or ambient light sensing. The signal fromchannel 426 can, for example, interrupt or be used for adjustingmeasurements associated with channel 427. As another example, channel426 can have a larger sampling area than channel 427. The lightdetectors can be associated with a certain channel based on the signalquality.

FIG. 4D illustrates multiple channels, where at least one channelincludes non-neighboring light detectors according to examples of thedisclosure. Channel 428 can include a first set of neighboring lightdetectors 404A and 404H and a second set of neighboring light detectors404D and 404E, where the first set can be spatially separated (i.e.,non-adjacent) along the concentric arrangement from the second set by atleast one other (i.e., not included in the same channel) light detector.Channel 429 can include a first set of neighboring light detectors 404Band 404C and a second set of neighboring light detectors 404F and 404G,where the first set can be spatially separated from the second set by atleast one other light detector. That is, one or more of the first andsecond channels can include two sets of adjacent light detectors (e.g.,a first set can include light detector 404A and light detector 404H),where the two sets can be non-adjacent (e.g., a second set can includelight detector 404D and light detector 404E, where the second set cannon-adjacent to the first set). The first and second channels can haveone or more different light detectors (e.g., light detector 404G may notbe included in both first and second channels).

In this channel association, one set of light detectors can measurepulsatile information, while the other set of light detectors canmeasure non-pulsatile (e.g., dark) information. For example, when lightemitter 406A is activated, pulsatile information for channel 428 can begenerated by light detector 404A and light detector 404H, but may not begenerated by light detector 404D and light detector 404E. Which lightdetector(s) measures pulsatile information for a given channel maydepend on the activated light emitter. For example, pulsatileinformation for the channel 428 may not be measured by the lightdetector 404A and the light detector 404H when another light emitter(e.g., light emitter 406B) is activated; the another light emitter maybe one that is not proximate to the respective light detector(s).Instead, the light detector 404D and the light detector 404E maygenerate pulsatile information when the light emitter 406B is activated.

In this manner, the same channel can effectively be used to measuredifferent locations. For example, the light emitter 406A and the lightemitter 406D can be assigned to the same channel 428. Signals measuredby a first one or more light detectors 404 in the channel may measureuseful information when one light emitter is active, while a second oneor more light detectors 404 in the same channel may not. Subsequently,the detectors that measure useful information (e.g., included in thedetermination of physiological information) may differ when anotherlight emitter is active.

FIG. 4E illustrates three channels, where each channel may includedifferent levels of signal information. The first association caninclude two sets of adjacent light detector, the two sets beingnon-adjacent (as discussed in the context of FIG. 4D), while the secondassociation can include one or more light detectors adjacent to at leastone light detector in the first association (e.g., light detector 404Gcan be adjacent to light detector 404H). For example, channel 430 caninclude the light detector 404A, the light detector 404H, the lightdetector 404D, and the light detector 404E. Channel 431 can include thelight detector 404B and the light detector 404G; and channel 432 caninclude the light detector 404C and the light detector 404F. With lightemitter 406A activated, the channel 430 may include the highest level ofpulsatile signal information, channel 431 may include a moderate level,and channel 432 may include the lowest level. With light emitter 406B orlight emitter 406D activated, the channel 431 and the channel 432 mayinclude the highest level of pulsatile signal information, and thechannel 430 may include the lowest level. With light emitter 406Cactivated, the channel 430 may include the highest level of pulsatileinformation, the channel 432 may include a moderate level, and thechannel 431 may include the lowest level.

In some examples, the binning and channel associations may bedynamically changed without user interaction. The channel associationcan be based on the mode of operation. For example, when the system isin a first measurement operation mode, the system can be configured witha single channel including all eight light detectors. When the systemswitches to a second measurement operation mode, the system candynamically switch to multiple (e.g., two, three, four, etc.) channels(e.g., as illustrated FIGS. 4A-4E).

In some examples, the system can switch to a certain channel associationbased on the measured signal information. For example, if the system isconfigured with two channels, as illustrated in FIG. 4A and the channel420 generates higher pulsatile signal information after a certain numberof measurements than the channel 421, the system may switch to thechannel association shown in FIG. 4C. If, after the channel associationswitch, the higher pulsatile signal information is associated with thechannel 427, the system may determine that one or more regions on theuser's skin (e.g., localized in close proximity to the channel 427) maybe most optimal for the given user. In this manner, the system can betailored to the user, user conditions (e.g., one or more materials, suchas the user's sleeve, inadvertently blocking optical components), and/orenvironmental conditions (e.g., higher levels of ambient light incidenton one or more light detectors).

The above discussed channel associations can be implemented inpost-processing where one or more (including all) of the light detectorscan be hardwired together. Examples of the disclosure can furtherinclude one or more switches for dynamically switching which lightdetectors are electrically coupled (e.g., hardwired) together.Additionally or alternatively, one or more light detectors and/orchannels may be deactivated. For example, if the system determines thatthe channel 427 (illustrated in FIG. 4C) includes the highest level ofpulsatile information, the system may deactivate light detectors (e.g.,light detector 404C, light detector 404D, light detector 404E, lightdetector 404F, light detector 404G, and light detector 404H) included inanother channel, such as channel 426, to save power.

FIG. 5 illustrates an exemplary block diagram of a computing systemcomprising the concentric architecture for optical sensing according toexamples of the disclosure. Computing system 500 can correspond to anyof the computing devices illustrated in FIGS. 1A-1C. Computing system500 can include a processor 510 configured to execute instructions andto carry out operations associated with computing system 500. Forexample, using instructions retrieved from memory, processor 510 cancontrol the reception and manipulation of input and output data betweencomponents of computing system 500. Processor 510 can be a single-chipprocessor or can be implemented with multiple components.

In some examples, processor 510 together with an operating system canoperate to execute computer code and produce and use data. The computercode and data can reside within a program storage block 502 that can beoperatively coupled to processor 510. Program storage block 502 cangenerally provide a place to hold data that is being used by computingsystem 500. Program storage block 502 can be any non-transitorycomputer-readable storage medium (excluding signals), and can store, forexample, history and/or pattern data relating to PPG signal andperfusion index values measured by one or more light detectors such aslight detectors 504. By way of example, program storage block 502 caninclude Read-Only Memory (ROM) 518, Random-Access Memory (RAM) 522, harddisk drive 508 and/or the like. The computer code and data could alsoreside on a removable storage medium and loaded or installed onto thecomputing system 500 when needed. Removable storage mediums include, forexample, CD-ROM, DVD-ROM, Universal Serial Bus (USB), Secure Digital(SD), Compact Flash (CF), Memory Stick, Multi-Media Card (MMC) and anetwork component.

Computing system 500 can also include an input/output (I/O) controller512 that can be operatively coupled to processor 510, or it can be aseparate component as shown. I/O controller 512 can be configured tocontrol interactions with one or more I/O devices. I/O controller 512can operate by exchanging data between processor 510 and the I/O devicesthat desire to communicate with processor 510. The I/O devices and I/Ocontroller 512 can communicate through a data link. The data link can bea one-way link or a two-way link. In some cases, I/O devices can beconnected to I/O controller 512 through wireless connections. By way ofexample, a data link can correspond to PS/2, USB, Firewire, IR, RF,Bluetooth or the like.

Computing system 500 can include a display device 524 that can beoperatively coupled to processor 510. Display device 524 can be aseparate component (peripheral device) or can be integrated withprocessor 510 and program storage block 502 to form a desktop computer(e.g., all-in-one machine), a laptop, handheld or tablet computingdevice of the like. Display device 524 can be configured to display agraphical user interface (GUI) including perhaps a pointer or cursor aswell as other information to the user. By way of example, display device524 can be any type of display including a liquid crystal display (LCD),an electroluminescent display (ELD), a field emission display (FED), alight emitting diode display (LED), an organic light emitting diodedisplay (OLED) or the like.

Display device 524 can be coupled to display controller 526 that can becoupled to processor 510. Processor 510 can send raw data to displaycontroller 526, and display controller 526 can send signals to displaydevice 524. Data can include voltage levels for a plurality of pixels indisplay device 524 to project an image. In some examples, processor 510can be configured to process the raw data.

Computing system 500 can also include a touch screen 530 that can beoperatively coupled to processor 510. Touch screen 530 can be acombination of sensing device 532 and display device 524, where thesensing device 532 can be a transparent panel that is positioned infront of display device 524 or integrated with display device 524. Insome cases, touch screen 530 can recognize touches and the position andmagnitude of touches on its surface. Touch screen 530 can report thetouches to processor 510, and processor 510 can interpret the touches inaccordance with its programming. For example, processor 510 can performtap and event gesture parsing and can initiate a wake of the device orpowering on one or more components in accordance with a particulartouch.

Touch screen 530 can be coupled to a touch controller 540 that canacquire data from touch screen 530 and can supply the acquired data toprocessor 510. In some cases, touch controller 540 can be configured tosend raw data to processor 510, and processor 510 can process the rawdata. For example, processor 510 can receive data from touch controller540 and can determine how to interpret the data. The data can includethe coordinates of a touch as well as pressure exerted. In someexamples, touch controller 540 can be configured to process raw dataitself. That is, touch controller 540 can read signals from sensingpoints 534 located on sensing device 532 and can turn the signals intodata that the processor 510 can understand.

Touch controller 540 can include one or more microcontrollers such asmicrocontroller 542, each of which can monitor one or more sensingpoints 534. Microcontroller 542 can, for example, correspond to anapplication specific integrated circuit (ASIC), which works withfirmware to monitor the signals from sensing device 532, process themonitored signals, and report this information to processor 510.

One or both display controller 526 and touch controller 540 can performfiltering and/or conversion processes. Filtering processes can beimplemented to reduce a busy data stream to prevent processor 510 frombeing overloaded with redundant or non-essential data. The conversionprocesses can be implemented to adjust the raw data before sending orreporting them to processor 510.

In some examples, sensing device 532 can be based on capacitance. Whentwo electrically conductive members come close to one another withoutactually touching, their electric fields can interact to form acapacitance. The first electrically conductive member can be one or moreof the sensing points 534, and the second electrically conductive membercan be an object 590 such as a finger. As object 590 approaches thesurface of touch screen 530, a capacitance can form between object 590and one or more sensing points 534 in close proximity to object 590. Bydetecting changes in capacitance at each of the sensing points 534 andnoting the position of sensing points 534, touch controller 540 canrecognize multiple objects, and determine the location, pressure,direction, speed, and acceleration of object 590 as it moves across thetouch screen 530. For example, touch controller 540 can determinewhether the sensed touch is a finger, tap, or an object covering thesurface.

Sensing device 532 can be based on self-capacitance or mutualcapacitance. In self-capacitance, each of the sensing points 534 can beprovided by an individually charged electrode. As object 590 approachesthe surface of the touch screen 530, the object can capacitively coupleto those electrodes in close proximity to object 590, thereby stealingcharge away from the electrodes. The amount of charge in each of theelectrodes can be measured by the touch controller 540 to determine theposition of one or more objects when they touch or hover over the touchscreen 530. In mutual capacitance, sensing device 532 can include a twolayer grid of spatially separated lines or wires (not shown), althoughother configurations are possible. The upper layer can include lines inrows, while the lower layer can include lines in columns (e.g.,orthogonal). Sensing points 534 can be provided at the intersections ofthe rows and columns. During operation, the rows can be charged, and thecharge can capacitively couple from the rows to the columns. As object590 approaches the surface of the touch screen 530, object 590 cancapacitively couple to the rows in close proximity to object 590,thereby reducing the charge coupling between the rows and columns. Theamount of charge in each of the columns can be measured by touchcontroller 540 to determine the position of multiple objects when theytouch the touch screen 530.

Computing system 500 can also include one or more light emitters such aslight emitters 506 and one or more light detectors such as lightdetectors 504 proximate to skin 520 of a user. Light emitters 506 can beconfigured to generate light, and light detectors 504 can be configuredto measure the return. Light detectors 504 can send measured raw data toprocessor 510, and processor 510 can perform noise and/or artifactcancelation to determine the PPG signal and/or perfusion index.Processor 510 can dynamically activate light emitters and/or lightdetectors based on an application, user skin type, and usage conditions.In some examples, some light emitters and/or light detectors can beactivated, while other light emitters and/or light detectors can bedeactivated to conserve power, for example. In some examples, processor510 can store the raw data and/or processed information in a ROM 518 orRAM 522 for historical tracking or for future diagnostic purposes.

In some examples, the light detectors can measure light information anda processor can determine a PPG signal and/or perfusion index from thereturn light. Processing of the light information can be performed onthe device as well. In some examples, processing of light informationneed not be performed on the device itself. FIG. 6 illustrates anexemplary configuration in which an electronic device is connected to ahost according to examples of the disclosure. Host 610 can be any deviceexternal to device 600 including, but not limited to, any of the systemsillustrated in FIGS. 1A-1C or a server. Device 600 can be connected tohost 610 through communications link 620. Communications link 620 can beany connection including, but not limited to, a wireless connection anda wired connection. Exemplary wireless connections include Wi-Fi,Bluetooth, Wireless Direct and Infrared. Exemplary wired connectionsinclude Universal Serial Bus (USB), FireWire, Thunderbolt, or anyconnection requiring a physical cable.

In operation, instead of processing light information from the lightdetectors on the device 600 itself, device 600 can send raw data 630measured from the light detectors over communications link 620 to host610. Host 610 can receive raw data 630, and host 610 can process thelight information. Processing the light information can includecanceling or reducing any noise due to artifacts and determiningphysiological signals such as a user's heart rate. Host 610 can includealgorithms or calibration procedures to account for differences in auser's characteristics affecting PPG signal and perfusion index.Additionally, host 610 can include storage or memory for tracking a PPGsignal and perfusion index history for diagnostic purposes. Host 610 cansend the processed result 640 or related information back to device 600.Based on the processed result 640, device 600 can notify the user oradjust its operation accordingly. By offloading the processing and/orstorage of the light information, device 600 can conserve space andpower-enabling device 600 to remain small and portable, as space thatcould otherwise be required for processing logic can be freed up on thedevice.

As discussed above, aspects in of the present technology include thegathering and use of physiological information. The technology may beimplemented along with technologies that involve gathering personal datathat relates to the user's health and/or uniquely identifies or can beused to contact or locate a specific person. Such personal data caninclude demographic data, date of birth, location-based data, telephonenumbers, email addresses, home addresses, and data or records relatingto a user's health or level of fitness (e.g., vital signs measurements,medication information, exercise information, etc.).

The present disclosure recognizes that a user's personal data, includingphysiological information, such as data generated and used by thepresent technology, can be used to the benefit of users. For example, auser's heart rate may allow a user to track or otherwise gain insightsabout their health or fitness levels.

The present disclosure contemplates that the entities responsible forthe collection, analysis, disclosure, transfer, storage, or other use ofsuch personal data will comply with well-established privacy policiesand/or privacy practices. In particular, such entities should implementand consistently use privacy policies and practices that are generallyrecognized as meeting or exceeding industry or governmental requirementsfor maintaining personal information data private and secure. Suchpolicies should be easily accessible by users, and should be updated asthe collection and/or use of data changes. Personal information fromusers should be collected for legitimate and reasonable uses of theentity and not shared or sold outside of those legitimate uses. Further,such collection/sharing should require receipt of the informed consentof the users. Additionally, such entities should consider taking anyneeded steps for safeguarding and securing access to such personalinformation data and ensuring that others with access to the personalinformation data adhere to their privacy policies and procedures.Further, such entities can subject themselves to evaluation by thirdparties to certify their adherence to widely accepted privacy policiesand practices. The policies and practices may be adapted depending onthe geographic region and/or the particular type and nature of personaldata being collected and used.

Despite the foregoing, the present disclosure also contemplatesembodiments in which users selectively block the collection of, use of,or access to, personal data, including physiological information. Forexample, a user may be able to disable hardware and/or software elementsthat collect physiological information. Further, the present disclosurecontemplates that hardware and/or software elements can be provided toprevent or block access to personal data that has already beencollected. Specifically, users can select to remove, disable, orrestrict access to certain health-related applications collecting users'personal health or fitness data.

A device is disclosed. In some examples, the device comprises: anoptical sensing unit comprising: a center region including: a pluralityof first light emitters configured to emit first light paths havingfirst wavelengths; one or more second light emitters configured to emitsecond light paths having second wavelengths, different from the firstwavelengths, wherein the plurality of first light emitters is locatedcloser to a peripheral region than the one or more second lightemitters; and the peripheral region located around the center region,the peripheral region including: a plurality of light detectorsconfigured to detect the first light paths and the second light paths,wherein the plurality of light detectors is oriented in a concentricarrangement. Additionally or alternatively, the device comprises: a lensincluding a plurality of regions, the plurality of regions including: afirst region overlaying the plurality of first light emitters; and asecond region overlaying the one or more second light emitters, whereinoptical properties of the first region differ from optical properties ofthe second region. Additionally or alternatively, in some examples, acenter of each light detector is located a first separation distanceaway from at least one of the one or more second light emitters.Additionally or alternatively, in some examples, each light detector islocated a first separation distance from one of the one or more secondlight emitters and a second separation distance from one of theplurality of first light emitters, wherein the first separation distanceis greater than the second separation distance. Additionally oralternatively, in some examples, another light detector is located athird separation distance from the one of the plurality of first lightemitters, wherein the third separation distance is greater than thefirst separation distance, the second separation distance, or both.Additionally or alternatively, in some examples, each of the pluralityof first light emitters is located at a radial angle relative to acenter of the center region, and edges of two of the plurality of lightdetectors are located at the radial angle relative to the center of thecenter region. Additionally or alternatively, in some examples, each ofthe first light emitters is located such that a separation distancebetween the respective first light emitter and one of the plurality oflight detectors is the same as the separation distance between therespective first light emitter and others of the plurality of lightdetectors, wherein the one of the plurality of light detectors and theother of the plurality of light detectors are adjacent light detectors.Additionally or alternatively, in some examples, the device furthercomprises: an optical isolation located between the plurality of firstand second light emitters and the plurality of light detectors.Additionally or alternatively, the optical isolation is ring-shaped.Additionally or alternatively, in some examples, walls of the opticalisolation define one or more cavities, wherein the plurality of firstlight emitters and the one or more second light emitters are located ina cavity separate from the plurality of light detectors. Additionally oralternatively, in some examples, the device further comprises: aretroreflector located between the center region and the peripheralregion, wherein the retroreflector is configured to reflect light in adirection away from at least one of the plurality of detectors.Additionally or alternatively, in some examples, the device furthercomprises: one or more windows located proximate to the center regionand the peripheral region; and an opaque mask located between the centerregion and the peripheral region, wherein the opaque mask is configuredto absorb light reflecting off an interface of the one or more windows.Additionally or alternatively, in some examples, the device furthercomprises: a selective transparent layer located in the peripheralregion, the selective transparent layer including a plurality of firstsections and a plurality of second sections, wherein the plurality offirst sections overlays one or more first portions of the peripheralregion and the plurality of second sections overlays one or more secondportions of the peripheral region, the one or more second portionsoverlay the plurality of light detectors. Additionally or alternatively,in some examples, the plurality of first sections includes material thatis partially transparent to the first wavelengths and transparent to thesecond wavelengths. Additionally or alternatively, in some examples, theplurality of second sections excludes material. Additionally oralternatively, in some examples, the selective transparent layer isring-shaped. Additionally or alternatively, in some examples, the devicefurther comprises: a Fresnel lens located in the center regionoverlaying the plurality of first light emitters and the one or moresecond light emitters; and one or more optical film sections located inthe peripheral region overlaying the plurality of light detectors,wherein the one or more optical film sections are configured to restrictlight passing through the peripheral region. Additionally oralternatively, in some examples, the first wavelengths include one ormore visible wavelengths, and the second wavelengths include one or moreinfrared wavelengths. Additionally or alternatively, in some examples,the first region of the lens is a Fresnel lens, and the second region ofthe lens includes a plurality of prisms.

A method for operating a device is disclosed. The method comprises:associating a plurality of light detectors to a plurality of channelsduring a first time; for each light emitter: emitting light from therespective light emitter; measuring at least a portion of the emittedlight by the one or more channels; and selecting and changing to anotherassociation such that at least one of the plurality of light detectorsis associated with a different channel during a second time, theselected another association based on one or more of the measurements.Additionally or alternatively, in some examples, the association duringthe first time or the second time includes each channel having adjacentlight detectors. Additionally or alternatively, in some examples, theassociation during the first time or the second time includes eachchannel having a first set of one or more of the plurality of lightdetectors and a second set of one or more of the plurality of lightdetectors, the first set spatially separated from the second set.Additionally or alternatively, in some examples, the method furthercomprises: determining a physiological information using the measurementfrom the first set when one light emitter is emitting and using themeasurement from the second set when another light emitter is emitting.Additionally or alternatively, in some examples, one associationincludes a single channel including all of the plurality of lightdetectors and another association includes multiple channels.Additionally or alternatively, in some examples, signals from the oneassociation are used for primary measurement information, and signalsfrom the other association are used for secondary measurementinformation. Additionally or alternatively, in some examples, theassociation during the first time includes two sets of adjacent lightdetectors, the two sets being non-adjacent. Additionally oralternatively, in some examples, at least one of the plurality of lightdetectors included in one of the plurality of channels during the firsttime is included in the same one of the plurality of channels during thesecond time.

Although the disclosed examples have been fully described with referenceto the accompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the disclosed examples as defined by the appended claims.

We claim:
 1. A wearable electronic device comprising: a device housing;a strap attached to the device housing and configured to retain thedevice housing on a user's wrist; a processor positioned within thedevice housing; and an optical sensing unit positioned at leastpartially within the device housing and comprising: a central region; aperipheral region surrounding the central region; a first light emitterpositioned in the central region and configured to emit first light in afirst wavelength range; a second light emitter positioned in the centralregion and configured to emit second light in a second wavelength rangethat is different from the first wavelength range; a set of lightdetectors positioned in the peripheral region and configured to detectthe first light and the second light, the set of light detectors atleast partially surrounding the first light emitter and the second lightemitter; and a selective transparent layer positioned in the peripheralregion and comprising: a first section positioned over a light detectorof the set of light detectors and transparent to the second wavelengthrange; and a second section surrounding the first section, the secondsection at least partially transparent to the first wavelength range andopaque to the second wavelength range.
 2. The wearable electronic deviceof claim 1, wherein: the first section of the selective transparentlayer is one of a set of first sections; each of the set of firstsections is positioned over a respective light detector of the set oflight detectors; and the second section surrounds each of the set offirst sections.
 3. The wearable electronic device of claim 1, wherein:the first wavelength range comprises infrared wavelengths; and thesecond wavelength range comprises visible light wavelengths.
 4. Thewearable electronic device of claim 1, wherein: the first section is atleast partially transparent to the first wavelength range; and thesecond section is fully transparent to the first wavelength range. 5.The wearable electronic device of claim 1, wherein the first section isan open portion of the selective transparent layer.
 6. The wearableelectronic device of claim 1, wherein: the wearable electronic devicefurther comprises a window positioned over the central region and theperipheral region of the optical sensing unit, the window defining aportion of an exterior surface of the wearable electronic device; andthe selective transparent layer is positioned along an interior surfaceof the window opposite the exterior surface.
 7. The wearable electronicdevice of claim 1, wherein: the optical sensing unit further comprises:a first wall that extends around the central region between the centralregion and the peripheral region; and a second wall that extends aroundthe peripheral region; the first light emitter and the second lightemitter are positioned in a first cavity at least partially defined bythe first wall; and the set of light detectors is positioned in a secondcavity that is at least partially defined by the first wall and thesecond wall and that extends around the first cavity.
 8. The wearableelectronic device of claim 7, wherein: the optical sensing unit furthercomprises an optical isolation configured to at least partially enclosethe first light emitter, the second light emitter, and the set of lightdetectors; and the first wall, the second wall, the first cavity, andthe second cavity cooperatively form the optical isolation.
 9. Thewearable electronic device of claim 7, wherein: the wearable electronicdevice further comprises a window positioned over the central region andthe peripheral region of the optical sensing unit, the window defining aportion of an exterior surface of the wearable electronic device; andthe optical sensing unit further comprises: a lens positioned betweenthe first cavity and the window; an optical film positioned between thesecond cavity and the window; a first opaque mask positioned between thefirst wall and the window and extending around the central region; and asecond opaque mask positioned between the second wall and the window.10. A wearable electronic device, comprising: a device housing definingan opening; a processor positioned within the device housing; a windowpositioned over the opening and defining a portion of an exteriorsurface of the wearable electronic device; an optical sensing unitpositioned beneath the window and comprising: a central region; a firstlight emitter positioned in the central region and configured to emitfirst light in a first wavelength range; a set of second light emittersarranged around the first light emitter and configured to emit secondlight in a second wavelength range that is different from the firstwavelength range; a set of light detectors arranged around the set ofsecond light emitters and configured to detect the first light and thesecond light; and a selective transparent layer positioned between theset of light detectors and the window and comprising: a set of firstsections, each of the set of first sections positioned over a respectivelight detector of the set of light detectors and at least partiallytransparent to the second wavelength range; and a second sectionsurrounding each of the set of first sections, the second sectiontransparent to the first wavelength range and at least partiallynon-transparent to the second wavelength range.
 11. The wearableelectronic device of claim 10, wherein the optical sensing unit furthercomprises a wall positioned between the set of second light emitters andthe set of light detectors and extending around the first light emitterand the set of second light emitters.
 12. The wearable electronic deviceof claim 11, wherein: the optical sensing unit further comprises a lenspositioned between the window and the first light emitter and the set ofsecond light emitters; and the wall extends around the lens.
 13. Thewearable electronic device of claim 11, wherein the optical sensing unitfurther comprises an opaque mask positioned between the wall and thewindow.
 14. The wearable electronic device of claim 13, wherein: thewall is a first wall; the opaque mask is a first opaque mask; and theoptical sensing unit further comprises: a second wall extending aroundthe set of light detectors; and a second opaque mask positioned betweenthe second wall and the window.
 15. The wearable electronic device ofclaim 11, wherein: the wall is a first wall; and the optical sensingunit further comprises: a second wall extending around the set of lightdetectors; and an optical film positioned between the set of lightdetectors and the window and between the first wall and the second wall.16. The wearable electronic device of claim 10, wherein: the firstwavelength range comprises infrared wavelengths; and the secondwavelength range comprises visible light wavelengths.
 17. An opticalsensing unit for a wearable electronic device comprising: an opticalisolation comprising: a first wall extending around and at leastpartially defining a first cavity; a second wall extending around thefirst wall and at least partially defining a second cavity between thefirst wall and the second wall; a first light emitter positioned in thefirst cavity and configured to emit first light in a first wavelengthrange; a second light emitter positioned in the first cavity andconfigured to emit second light in a second wavelength range differentfrom the first wavelength range; a set of light detectors positioned inthe second cavity of the optical sensing unit and configured to detectthe first light and the second light; and a selective transparent layerpositioned over the second cavity and comprising: a first section thatis transparent to the second wavelength range; and a second sectionsurrounding the first section, the second section at least partiallytransparent to the first wavelength range and opaque to the secondwavelength range.
 18. The optical sensing unit of claim 17, furthercomprising: a Fresnel lens positioned over the first light emitter; anda prism positioned over the second light emitter.
 19. The opticalsensing unit of claim 17, wherein: the second light emitter is one of aset of second light emitters; and the set of second light emitters isarranged around the first light emitter.
 20. The optical sensing unit ofclaim 19, wherein: the optical sensing unit further comprises: a firstlens region positioned over the first light emitter and comprising aFresnel lens; and a second lens region positioned over the set of secondlight emitters and comprising a set of prisms, each prism of the set ofprisms positioned over a respective second light emitter of the set ofsecond light emitters.